PROJECT ABSTRACT/SUMMARY Despite important advances in the treatment of learning disabilities (LDs), the dominant approach to intervention?direct skills instruction?fails to meet the needs of 25-40% of LD students. Innovative approaches are therefore required to target the specific needs of subgroups of LD students in order to expand the framework for LD intervention. This Project addresses a subset of the LD population that (a) has been understudied, (b) experiences disproportionately poor response to intervention, and (c) represents an LD subtype with a distinctive set of needs. These students have difficulty that spans math problem solving (MPS) & reading comprehension (RC). We refer to this LD subtype as higher-order comorbid LDs. With this understudied population, a transdisciplinary team of researchers, spanning learning sciences, second language learning, LDs, and developmental psychology, investigate a high-risk innovative approach to LD intervention. This approach involves embedding language comprehension (LC) instruction in direct skills intervention, with instructional scaffolding to explicitly connect MPS, RC, & LC demands. Comorbid students (with co-occurring difficulty in MPS & RC) are randomly assigned to (1) LC instruction embedded in direct MPS intervention with scaffolding to connect MPS, RC, & LC demands; (2) LC instruction embedded in direct RC intervention with scaffolding to address MPS, RC, & LC demands; or (3) a control group. We test aligned and reciprocal effects of each condition on MPS & RC outcomes, and we test LC as a mediator of those effects. We also explore the robustness of these effects by examining the pattern of intervention effects for boys vs. girls and for native vs. non-native English speakers. This Project impacts science by testing the comorbidity hypothesis: LC plays a critical role in MPS and RC and provides direction for understanding this form of LD comorbidity and for offering a coordinated, efficient approach to improve both outcomes. This Project also impacts clinical practice by addressing higher-order comorbidity (MPS+RC difficulty) as an LD subtyping framework in a theoretically coordinated manner to simultaneously improve outcomes in two academic domains that are critical for successful life outcomes.